A
1. A
the blood group whose red cells carry the A antigen [kri skupine, kjer rdeče krvne celice nosijo antigen A]
2. a, A
the 1st letter of the Roman alphabet [prva črka rimske abecede]
3. A, vitamin A
any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes [katerikoli izmed več maščobotopnih vitaminov, ki so ključni za normalen vid; preprečuje nočno slepoto, vnetje ali suhost oči.]
4. adenin, A
(biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA [(biokemija) purinska baza, ki se nahaja v DNK in RNK; pareira se s timinom v DNK in z uracilom v RNK]